25 Jul
2007
25 Jul
'07
2:19 p.m.
There may have
neen an N-diagram for it (there's an archive of
these on the web -- do a google search for 'N-diagram')....
Thanks, I'll go take a look. I suppose I should sit down and trace out the
circuits. Most of the
"complicated" stuff seems to be on the keypad (the DTMF encoder), the rest
looks fairly straightforward.
Most 'phones since the 806 have essentially rhe same cirucit (apart from
things like the dialer -- is it a mechancial dial, a pulse-dialing keypad
[1] or a DTMF keypad). Be warned that while there aren't many components
in said circuit, it is not at all easy to understand. Some components do
2 or 3 jobs at different times(!).
[1] IIRC that keypad, at least the GPO vaesion, often has a NiCd battery
connected to it to keep it alive during dailing.
-tony